/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.kie.dmn.feel.runtime.functions;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.kie.dmn.api.feel.runtime.events.FEELEvent.Severity;
import org.kie.dmn.feel.runtime.events.InvalidParametersEvent;
import org.kie.dmn.feel.runtime.functions.extended.ContextPutFunction;

public class GetEntriesFunction extends BaseFEELFunction {

    public static final GetEntriesFunction INSTANCE = new GetEntriesFunction();

    public GetEntriesFunction() {
        super("get entries");
    }

    public FEELFnResult<List<Object>> invoke(@ParameterName("m") Object m) {
        if (m == null) {
            return FEELFnResult.ofError(new InvalidParametersEvent(Severity.ERROR, "m", "cannot be null"));
        }
        return ContextPutFunction.toMap(m).map(GetEntriesFunction::toEntries);
    }

    private static List<Object> toEntries(Map<?, ?> m) {
        List<Object> result = m.entrySet().stream()
                                             .map(kv -> {
                                                 Map<Object, Object> entry = new HashMap<>();
                                                 entry.put("key", kv.getKey());
                                                 entry.put("value", kv.getValue());
                                                 return entry;
                                             })
                                             .collect(Collectors.toList());
        return result;
    }
}
